The instant invention relates to an aircraft wing constructed from a plurality of aluminum alloy workpieces. More particularly, a pair of opposed top and bottom wing boxes are machined from single pieces of aluminum alloy. Each wing box has a wing skin surface integral with stiffeners and ribs to provide a tailored stiffness wing construction. The machined wing skin surfaces provide for a very smooth and accurate air flow over the wing.
Conventional aircraft wing construction generally comprises one or more spars or spar webs that extend laterally relative to the longitudinal axis of the airframe for the support of a plurality of longitudinally extending laterally spaced ribs that define the shape of the air foil. Vertical web portions of the spars carry shear loads imposed on the wing and the upper and lower wing skins act as flanges that sustain the wing under bending and torsional loads.
A variation on the aforementioned conventional aircraft wing construction is taught in Barkley, U.S. Pat. No. 2,122,709. Barkley discloses a wing constructed of a plurality of laterally extending webs that support the wing skins in a manner that makes it unnecessary to utilize longitudinally extending ribs. The Barkley wing configuration, however, does nothing to solve the problem known as aeroelastic divergence. Aeroelastic divergence occurs when a forward swept wing bends upwardly due to high angles of attack or gust loads. Because of the forward sweep geometry of the wing, the resultant torsional deflection increases the angle of attack of the wing. The increase in angle of attack of the wing increases aerodynamic load still further causing yet additional increases in the angle of attack. This self-propagating "divergence" can lead to structural damage or failure of the wing. Additionally, the Barkley wing configuration does not allow for the use of composite materials in wing construction.
U.S. Pat. No. 5,332,178 to Williams, and assigned to the assignee of the instant invention, addresses the problem of aeroelastic divergence by providing for an aircraft wing construction having a plurality of elongated hollow spars arranged in a generally parallel relation in an array to define the surface of an airfoil with a composite skin disposed about the assembled spars. The fiber reinforced spar configuration, coupled with orientation of composite fibers within the wing skin alters the elastic configuration of the wing wherein an increase in aerodynamic load twists the wing in a direction so as to reduce the angle of attack of the wing thereby reducing aerodynamic load under turbulent conditions.
The Williams wing configuration, however, does not provide for the use of traditional wing construction materials, resulting in a composite material wing that is quite expensive and labor intensive. The instant invention provides for an aircraft wing that is constructed from a pair of aluminum alloy wing boxes shaped by known-in-the-art machine tool processes, thereby dramatically reducing the labor required for operations such as riveting and welding in conventional wing construction, or fiber lay-up in composite wing construction. In addition to the reduction in labor costs, the instant invention provides for extremely accurate wing skin surfaces, thereby minimizing aerodynamic drag and the attendant costs thereof.